Yesterday I did a little work on the Jefferson County Place Names directory. This enormous database, accessible online, ought to be more widely known, so here's an unsolicited advertorial for it. With more than 3,000 entries, it's only a start--but in theory, and often in reality, it can provide historical and location data on names to researchers and other interested parties. The original Place Names project, sponsored by the Jefferson Co. Historical Commission in the 1980s-90s, represents a huge effort by dozens of local historians.
The link above displays a search page, into which you can type a word or a specific place name to retrieve instances. You can also click on an alphabetic index at the bottom of the page for all entries starting with "K," for example. Give it a try!
Here's an example of one of the "new" entries I added yesterday: the St. Vrain, Golden City, and Colorado Wagon Road. The information comes from an Historic Contexts report, produced in 2002 as part of a county-wide cultural resources survey.